Which of the following statements BEST describes an application server?

A.
Application servers are the most common server products in use and provide multiple services.

B.
Application servers are configured to run programs that can be accessed by multiple users.

C.
Application servers provide either a single service, or related services.

D.
Application servers combine related server types into clusters.

Explanation:
Application servers are configured to run programs that can be accessed by multiple users.
Incorrect
Answers:
A: General purpose servers are the most common server products in use and provide multiple services, such email, file, print, and web services that run on an industry-standard network operating system (NOS).
C: Appliance servers provide either a single service, or related services, such as Internet caching and firewall protection.
D: A multi-tiered server structure combines related server types into clusters and can be subdivided into front-end, mid-tier, and back-end servers.
References:
Charles J. Brooks, Server+ Certification Exam Cram 2 (Exam SK0-002), QUE Publishing, Indianapolis, 2006, pp. 8-29.